The disclosure generally relates to a system for supplying fuel to an engine, e.g., an internal combustion engine that powers a vehicle such as an automobile. More particularly, the disclosure relates to a fuel supply system in which a pre-determined voltage is applied to an electric motor configured to drive a pump in the system where the pump may be feedback controlled such that an actual and/or observed fuel pressure throughout the system approaches a target and/or ideal fuel pressure.
Readily available fuel-supply systems may include those disclosed by U.S. Patent Application Publication No. 2014/0174403 (also published as Japanese Laid-Open Patent Publication No. 2014-122585). Such a fuel-supply system supplies fuel stored in a fuel tank to an engine in communication with the fuel tank by varying pressure across the system, i.e. such that a fluid, such as the stored fuel, may flow from the fuel tank to the engine as desired. In detail, the fuel supply system includes a fuel pump driven by a motor and a pressure controller that controls fuel pressure while the fuel is distributed throughout the fuel system by the fuel pump. Moreover, the pressure controller may control fuel pressure upon receiving feedback from the fuel system, i.e. referred to in the art as “feedback control.” Such feedback control adjusts the fuel pump as necessary to ensure that an actual and/or observed fuel pressure approaches a target and/or ideal fuel pressure value. To assist in the fuel system performing feedback control as described here, an engine control unit (“ECU”) transmits a signal representing a target fuel pressure value to the pressure controller. Further, a power supply device, such as a battery, may supply electric power to the ECU, the motor and the pressure controller when a power switch, such as an ignition switch of an automobile, is activated.
As often associated with currently available fuel-supply systems, and also that shown by an exemplary embodiment of the current disclosure in FIG. 11 herein, a pressure controller may not receive target fuel pressure information, i.e. a signal, during a “wait” and/or “delay” period Ams, such as between time T0 and T1 immediately following ignition of the engine. This delay of the target fuel pressure signal may result from a lack of preparation of the ECU as needed to transmit the target fuel pressure value signal until said time T1. Thus, during the period Ams, the controller may not be able to perform feedback control based on a target fuel pressure value. Accordingly, during the period Ams as shown by FIG. 11, a ratio of voltage applied to the fuel pump motor (hereinafter referred to as a “motor duty ratio”) may be set to a maximum possible value (see a lower portion of FIG. 11) that takes into account the relative ease of activating the engine, etc. Nevertheless, should the motor duty ratio be set to the maximum value as described here, the fuel pump may respond to such a maximum setting by overshooting a desired and/or target fuel pressure, or otherwise cause undesirable increases in power consumption across the fuel-supply system.
In view of the above, there is a current need in the art for a fuel-supply system that controls fuel pressure across the system until a target fuel pressure value signal is received after the motor is started.